CEREBRAL MICROEMBOLISM DURING CAROTID ENDARTERECTOMY

BACKGROUND: This study was designed to assess the intraoperative risk of cerebral microembolism, as detected by transcranial Doppler ultraso nography, during carotid endarterectomy. PATIENTS AND METHODS: Thirty- six patients (37 procedures) with symptomatic (n = 35) or asymptomatic (n = 2) internal carotid artery origin stenosis (>50% were monitored continuously during carotid endarterectomy. Special instrumentation wa s used to detect high-intensity transient signals (HITS) in the middle cerebral artery on the carotid endarterectomy side. All HITS satisfie d a priori established criteria. RESULTS: The incidence of carotid end arterectomies with formed-element HITS increased at clamp release (23/ 37, P <0.001) and shunt opening (7/11, P = 0.014), and during wound cl osure (13/22, P <0.005) and shunting (5/11, P = 0.046), HITS with air microbubble characteristics were detected at clamp release (22/37, P < 0.001) and shunt opening (5/11, P = 0.025). CONCLUSIONS: HITS do not o ccur randomly during carotid endarterectomy. Shunting, unclamping, and wound closure are high-risk periods.